Android中用代码设置按钮在RelativeLayout中居中

效果图

MainActivity中

package com.zhh.centertest;

import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.RelativeLayout;

public class MainActivity extends Activity {
//  相对布局
    private RelativeLayout rlBuJu;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        rlBuJu = findViewById(R.id.rlBuJu);

//      实例化一个按钮对象
        Button button = new Button(this);
        button.setText("居中");
//      实例化一个layoutParams，
//      如果父布局是相对布局则RelativeLayout.LayoutParams
//      如果父布局是线性布局则是LinearLayout.LayoutParams
        RelativeLayout.LayoutParams layoutParams =
                new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
//      居中
        layoutParams.addRule(RelativeLayout.CENTER_IN_PARENT);
//      设置属性
        button.setLayoutParams(layoutParams);
//      把按钮添加到布局中
        rlBuJu.addView(button);
    }


}

activity_main中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:id="@+id/rlBuJu"
    >



</RelativeLayout>